Three devices are connected to the fieldbus network. Each of them can initiate a transmission with one of the other two on average every 15 seconds according to the exponential distribution (since the completion of the previous one that was initiated) and it lasts exactly 1 second. If the device not participating in the transmission encounters a busy network, then it retries the transmission exactly after 0.3 second. After one hour of simulation, observe the average network busy and the number of collisions. Build a model using the concept of activity selection